AG2 is a production-grade Python framework for building multi-agent AI systems. It provides a unified agent abstraction with support for multiple LLM providers (OpenAI, Anthropic, Gemini, Mistral, Bedrock, Ollama, xAI, Z.AI, DashScope), protocol integrations (A2A, A2UI, MCP, ACP), and sandboxed code execution (Docker, Daytona, local). The architecture is event-driven with a modular middleware pipeline, dependency injection, and a streaming event bus. It includes a full evaluation suite with trace reconstruction, scorers, pairwise comparison, and result persistence. The network layer enables distributed agent coordination via a hub-and-channel model with WAL persistence, identity management, and transport-agnostic envelopes. The framework also supports real-time voice interaction, skills-based toolkits, knowledge stores, and human-in-the-loop workflows. While the surface area is large, the codebase demonstrates high craftsmanship with clean abstractions, protocol-based interfaces, and extensive test coverage across all modules.